Marine jet propulsion apparatus

ABSTRACT

A tubular casing having separable front and rear sections is secured at its front end to the transmission housing of a conventional outboard motor assembly. In lieu of the usual propeller element, a bladed impeller designed for operation in a closed space is fixed on a propeller shaft which projects rearwardly from the transmission housing into the casing. A bearing support located within and fixed to the rear section of the casing is formed with a through opening aligned with the shaft, and seated in this opening is a bearing unit into which the rear end of the propeller shaft extends. In order to enable installation of the rear section of the casing (following installation of the front section), it must be capable of assuming a tilted orientation before being brought into registry with the front section and while being moved forwardly past a gas discharge duct projecting from the transmission housing. Such tilting is made possible by postponing insertion of the bearing unit into the bearing support until after the rear section of the casing is in place.

United States Patent 1 Hall [ Nov. 26, 1974 MARINE JET PROPULSIONAPPARATUS Inventor: Kimball P. Hall, Shoreham, N.Y.

Hall Marine Corporation, Shoreham, N.Y.

Filed: Apr. 3, 1972 Appl. No.: 240,693

Assignee:

References Cited UNITED STATES PATENTS Schmidt 415/142 X PrimaryExaminer-Clarence R. Gordon Attorney, Agent, or Firm-Emile Paul [5 7ABSTRACT A tubular casing having separable front and rear sections issecured at its front end to the transmission housing of a conventionaloutboard motor assembly. In lieu of the usual propeller element, abladed impeller designed for operation in a closed space is fixed on apropeller shaft which projects rearwardly from the transmission housinginto the casing. A bearing support located within and fixed to the rearsection of the casing is formed with a through opening aligned with theshaft, and seated in this opening is a bearing unit into which the rearend of the propeller shaft extends. In order to enable installation ofthe rear section of the casing (following installation of the frontsection), it must be capable of assuming a tilted orientation beforebeing brought into registry with the front section and while being movedforwardly past a gas discharge duct projecting from the transmissionhousing. Such tilting is made possible by postponing insertion of thebearing unit into the bearing support until after the rear section ofthe casing is in place.

13 Claims, 5 Drawing Figures MARINE JET PROPULSION APPARATUS Myinvention is concerned with marine propulsion apparatus designed to besubstituted for the propeller element of a conventional marinepropulsion device, whereby the latter may be converted to a shroudedimpeller or pump jet system, and represents a further development of theapparatus disclosed in my prior U.S. Pat. No. 3,389,558.

The present invention affords the same basic advantages as those notedin my prior patent, viz., reducing the hazards to swimmers, waterskiers, etc., in the vicinity, protecting the rotor elements frominterference and damage by foreign objects, and improving the effciencyand performance of the propulsion system. In addition, by utilizing asectional shroud construction, in conjunction with a novel design of thebearing structure supporting the rear end of the propeller shaft, theapparatus becomes particularly suitable for effecting the conversion ofcertain conventional systems embodying a gas discharge duct.

It is an object of the invention to utilize a bearing structure havingan outer, hollow bearing support fixed within the rear section of theshroud, and an inner bearing unit insertable into and removable from theouter support through the rear end of the shroud.

It is another object to utilize a shroud having releasably connectedfront and rear sections and means for attaching the front section to apreexisting marine propulsion system having agas discharge duct.

It is still another object to provide passageways in and adjacent thebearing structure to enable the flow of water to and from the bearingsurfaces when the apparatus is operating in its normal environment.

It is still another object to utilize an outer bearing support whoseinternal dimensions are adequate to permit moving the rear shroudsection in a tilted attitude past the gas discharge duct during assemblyof the apparatus.

These and other objects of the invention will become apparent in thelight of the detailed description which follows in conjunction with theaccompanying drawings, wherein:

FIG. 1 is a side view partially in section;

FIG. 2 is a detail sectional view taken along line 22 of FIG. 1;

FIG. 3 is a detail sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is a detail view of an alternative construction for the mountingof the bearing liner; and

FIG. 5 is a sectional side view showing an alternative impeller mountingarrangement.

An example ofa marine propulsion system converted according to myinvention is shown in FIG. 1. It includes parts of a conventionaloutboard motor apparatus, viz., transmission housing 2, anti-cavitationplate 4, exhaust gas outlet 6, and rearwardly projecting propeller shaft8. Instead of the usual propeller element, however, a bladed rotaryimpeller 10, designed for operation within a closely fitting externalshroud, is fixed to the propeller shaft by a pin 11 for rotationtherewith.

The shroud is of sectional construction, being composed of a frontsection 12 and a rear section 14, the front section being attached atits front end to the anticavitation plate 4 by a lug and bracketmounting 16,

18, at the top, and to the transmission housing by a strap mounting 20at the bottom.

The rear shroud section 14 is releasably connected at its forward end tothe rear of the front section 12 by threaded bolts, one of which isshown at 22 in FIG. 1. Also shown in this figure is a rearwardlyextending external trough or channel 24 formed in the top of the rearshroud section. When the parts of the apparatus have been assembled, thedownwardly projecting gas discharge duct 6 will project into the channel24, whereby an improved flow of the exhaust gases will be effected.

The novel bearing structure for engaging the rear end of the propellershaft includes an outer bearing support .26 positioned within the rearshroud section and fixed thereto by struts or vanes 28. Extendingthrough the bearing support 26 is a passageway aligned with thepropeller shaft and formed with a cylindrical bore 30 at the rear and anexpanded forward chamber 32. The bearing unit 34 seated in the bore 30is insertable into and removable from the bearing support 26 through theopen rear end of shroud section 14. It is-provided with a forwardlyfacing shoulder 36 which, in its working position, engages the rear endof bearing support 26. Releasable means 38 retains the bearing unit 34in its working position relative to the bearing support 26. For readyaccess to the means 38, a removable plug 39 is provided in the wall ofshroud section 14. At its forward end, the bearing unit 34 is providedwith a large diameter bore 40 having an annular recess within which isseated a bearing liner 42 made of rubber or rubber-like material andhaving .a longitudinally grooved inner surface. The liner 42 may besupplied in the form of a flat strip, then rolled into cylindrical shapeand inserted into the bore 40.

Alternatively, if desired, the bearing liner may be mounted in themanner illustrated in FIG. 4, wherein numeral 43 designates a bronzesleeve which has been pressed into the bearing unit 34; numeral 42designates a rubber bearing liner vulcanized inside the sleeve 43; andnumeral 45 designates one of the longitudinal grooves formed in theliner.

Extension nut 44 is fitted over the rear end of propeller shaft 8 inthreaded engagement therewith. Tightening nut 44 locks the hub 46 ofimpeller 10 against pin 11, which engages a groove 48 formed in theimpeller hub. The nut is retained in its working position by releasablemeans 50; it extends into the bore 40 and rotatably engages the innersurface of bearing liner 42.

The impeller mounting just described is adapted for the conversion of anumber of existing models of outboard motors; however, I haveadditionally shown, in FIG. 5 of the drawings an alternativeconstruction which is more suitable for use with certain other models.In the latter construction, an extension nut 47 is threadedly connectedto the rear end of the propeller shaft, but is retained by a cotter pin51 which is independent of the impeller hub 46. The torque istransmitted from the propeller shaft to the impeller by splines 49, andthe axial thrust is transmitted by the .pin 13.

Lubrication and cooling of the rubber bearing liner 42 is obtained bywater flowing downstream through the horizontal grooves formed in theliner. Flow of water through the bearing is assured by an axialpassageway 52 which leads rearwardly from bore 40, thereby providingcommunication between the bearing liner 42 and the rear outlet of theshroud, and by the gap 56 between the impeller hub and the bearingsupport. By virtue of this arrangement a portion of the water enteringthe shroud is diverted through gap 56 to liner 42, through thelongitudinal grooves therein, and thence through bore 40 and passageway52 and reardwardly out of the shroud, whereby the bearing is continuallylubricated. To facilitate removal of bearing unit 34, the passageway isthreaded internally, as shown at 54, for engagement with an externallythreaded pulling tool.

The composite structure formed by bearing support 26 and bearing unit 34is shaped externally in the form of a streamlined rearwardly taperedbody to obtain optimum flow of fluid througn the apparatus with minimumresistance. For the same reason, the stator vanes 28 are of streamlinedcross-sectional shape. The preferred shape is that of a camberedairfoil, or hydrofoil, oriented so as to straighten the fluid flow andneutralize the torque effect of the rotating impeller.

An important advantage of my novel construction is that it lends itselfto easy and rapid assembly when utilized in the conversion ofa-propeller-type marine propulsion system having the exhaust gasdischarge duct arrangement shown in FIG. 1. If bearing parts 26, 34 weremade in one piece, the step of fitting the bearing structure to theextension nut 44 would require maintaining the bearing structure inco-axial alignment with the propeller shaft while simultaneouslydisplacing forwardly the bearing structure together with the attachedshroud section. Such a step would be rendered impossible by theinterference of projecting duct 6. However, with the bearing structureherein disclosed, this difficulty is overcome by postponing insertion ofthe bearing unit 34 until after the shroud sections have been installed.The dimensions of bore 30 and chamber 32are such that, with the innerbearing unit omitted, there is sufficient play to permit rear section 14to be displaced forwardly in a tilted attitude past duct 6 and thenreoriented and connected to the front section 12. At this point it is asimple matter to insert bearing unit 34 forwardly through the rear endof section 14 and into. bore I claim:

1. Marine propulsion apparatus comprising a front tubular element and arear tubular element, the interior surface of said front element beingin the form ofa surface of revolution about a central axis, the rear endof said front element conforming in size and shape to the front end ofsaid rear element, releasable means securing said front end of said rearelement to the rear end of said front element in fixed, contiguousrelation, whereby said elements constitute a single continuous tubularcasing, a bearing support within said rear element, said support havingan opening therethroudh coaxial with said axis, means connecting saidsupport in fixed relation to and spaced from the interior surface ofsaid rear element, a bearing unit disposed in said opening, said bearingunit having an internal bearing surface co-axial with said axis andbeing insertable into and removable from said opening through the rearend of said rear element, means releasably connecting said bearing unitin fixed relation to said support, an outboard motor transmissionhousing, means securing the front end of said front element to saidhousing, a power-driven shaft extending rearwardly from said housing inalignment with said axis, the rear end of said shaft being rotatablysupported in said bearing unit, a bladed impeller unit in said frontelement mounted on said shaft for rotation therewith, and a gasdischarge duct extending downwardly and rearwardly from said housing,said rear element having an external channel in its top portionextending rearwardly and in alignment with the outlet end of said gasdischarge duct.

2. The structure recited in claim 1 and wherein said bearing unit has anoutwardly extending forwardly facing shoulder at its rear end engageablewith the rear end of said support, thereby limiting to a predeterminedposition the forward displacement of said bearing unit relative to saidsupport.

3. The structure recited in claim 2 and wherein said bearing unit ischaracterized by internal passageways providing communication betweensaid bearing surface and the rear end of said tubular casing, and saidbearing support and bearing unit are axially spaced from said impellerunit to provide communication between said bearing surface and the frontend of said tubular casing, whereby a lubricating flow of water throughthe bearing is obtained during the normal operation of said apparatus.

4. The structure recited in claim 3 and wherein said support and saidbearing unit in assembled condition form a fairing element having arearwardly tapered, streamlined outer surface.

5. The structure recited in claim 4 and wherein said bearing surface ismade of rubber formed with longitudinally disposed grooves.

6. The structure recited in claim 5 and wherein the transversedimensions of said opening are such as to permit a certain amount oftilting of said rear element relative to said axis during assembly,whereby in assembling the apparatus the front end of said rear elementmay be readily moved past said gas discharge duct and connected to thefront element after said front element has been secured to saidtransmission housing and prior to insertion of said bearing unit.

7. Marine propulsion apparatus comprising a front tubular element and arear tubular element, the interior surface of said front element beingin the form ofa surface of revolution about a central axis, the rear endof said front element conforming in size and shape to the front end ofsaid rear element, releasable means securing said front end of said rearelement to the rear end of said front element in fixed, contiguousrelation, whereby said elements constitute a single continuous tubularcasing, a bearing support within said rear element, said support havingan opening therethrough coaxial with said axis, means connecting saidsupport in fixed relation to and spaced from the interior surface ofsaid rear element, a bearing unit disposed in said opening, said bearingunit having an internal bearing surface coaxial with said axis and beinginsertable into and removable from said opening through the rear end ofsaid rear element, means releasably connecting said bearing unit infixed relation to said support, an outboard motor transmission housing,means securing the front end of said front element to said housing, apower-driven shaft extending rearwardly from said housing in alignmentwith said axis, the rear end of said shaft being rotatably supported insaid bearing unit, and a bladed impeller unit in said front elementmounted on said shaft for retation therewith, wherein aid bearing unithas an outwardly extending forwardly facing shoulder at its rear endengageable with the rear end of said support, thereby limiting to apredetermined position the forward displacement of said unit relative tosaid support.

8. The structure recited in claim 7 and wherein said bearing unit ischaracterized by internal passageways providing communication betweensaid bearing surface and the rear end of said tubular casing, and saidbearing support and bearing unit are axially spaced from said impellerunit to provide communication between said bearing surface and the frontend of said tubular casing, whereby a lubricating flow of water throughthe bearing is obtained during the normal operation of said apparatus.

9. The structure recited in claim 8 and wherein said support and saidbearing unit in assembled condition form a fairing element having arearwardly tapered,

streamlined outer surface.

10. The structure recited in claim 9 and wherein said bearing surface ismade of rubber formed with longitudinally disposed grooves.

11. Marine propulsion apparatus comprising a front tubular element and arear tubular element, the interior surface of said front element beingin the form ofa surface of revolution about a central axis, the rear endof said front element conforming in size and shape to the front end ofsaid rear element, releasable means securing said front end of said rearelement to the rear end of said front element in fixed, contiguousrelation, whereby said elements constitute a single continuous tubularcasing, a bearing support within said rear ele ment, said support havingan opening therethrough coaxial with said axis, means connecting saidsupport in fixed relation to and spaced from the interior surface ofsaid rear element, a bearing unit disposed in said opening, said bearingunit having an internal bearing surface co-axial with said axis andbeing insertable into and removable from said opening through the rearend of said rear element, means releasably connecting said bearing unitin fixed relation to said support, an outboard motor transmissionhousing, means securing the front end of said front element to saidhousing, a power-driven shaft extending rearwardly from said housing inalignment with said axis, the rear end of said shaft being rotatablysupported in said bearing unit, and a bladed impeller unit in said frontelement mounted on said shaft for rotation therewith, wherein saidbearing unit is characterized by internal passageways providingcommunication between said bearing surface and the rear end of saidtubular casing, and said bearing support and bearing unit are axiallyspaced from said im' peller unit to provide communication between saidbearing surface and the front end of said tubular casing, whereby alubricating flow of water through the bearing is obtained during thenormal operation of said apparatus.

12. The structure recited in claim 1 and wherein said bearing unit ischaracterized by internal passageways providing communication betweensaid bearing surface and the rear end of said tubular casing, and saidbearing support and bearing unit are axially spaced from said impellerunit to provide communication between said bearing surface and the frontend of said tubular casing, whereby a lubricating flow of water throughthe bearing is obtained during the normal operation of said device,

13. The structure recited in claim 1 and wherein the transversedimensions of said opening are such as to permit a certain amount oftilting of said rear element relative to said axis during assembly,whereby in assembling the deivce the front end of said rear element maybe readily moved past said gas discharge duct and connected to the frontelement after said front element has been secured to said transmissionhousing and prior to insertion of said bearing unit.

1. Marine propulsion apparatus comprising a front tubular element and arear tubular element, the interior surface of said front element beingin the form of a surface of revolution about a central axis, the rearend of said front element conforming in size and shape to the front endof said rear element, releasable means securing said front end of saidrear element to the rear end of said front element in fixed, contiguousrelation, whereby said elements constitute a single continuous tubularcasing, a bearing support within said rear element, said support havingan opening therethrough co-axial with said axis, means connecting saidsupport in fixed relation to and spaced from the interior surface ofsaid rear element, a bearing unit disposed in said opening, said bearingunit having an internal bearing surface coaxial with said axis and beinginsertable into and removable from said opening through the rear end ofsaid rear element, means releasably connecting said bearing unit infixed relation to said support, an outboard motor transmission housing,means securing the front end of said front element to said housing, apowerdriven shaft extending rearwardly from said housing in alignmentwith said axis, the rear end of said shaft being rotatably supported insaid bearing unit, a bladed impeller unit in said front element mountedon said shaft for rotation therewith, and a gas dIscharge duct extendingdownwardly and rearwardly from said housing, said rear element having anexternal channel in its top portion extending rearwardly and inalignment with the outlet end of said gas discharge duct.
 2. Thestructure recited in claim 1 and wherein said bearing unit has anoutwardly extending forwardly facing shoulder at its rear end engageablewith the rear end of said support, thereby limiting to a predeterminedposition the forward displacement of said bearing unit relative to saidsupport.
 3. The structure recited in claim 2 and wherein said bearingunit is characterized by internal passageways providing communicationbetween said bearing surface and the rear end of said tubular casing,and said bearing support and bearing unit are axially spaced from saidimpeller unit to provide communication between said bearing surface andthe front end of said tubular casing, whereby a lubricating flow ofwater through the bearing is obtained during the normal operation ofsaid apparatus.
 4. The structure recited in claim 3 and wherein saidsupport and said bearing unit in assembled condition form a fairingelement having a rearwardly tapered, streamlined outer surface.
 5. Thestructure recited in claim 4 and wherein said bearing surface is made ofrubber formed with longitudinally disposed grooves.
 6. The structurerecited in claim 5 and wherein the transverse dimensions of said openingare such as to permit a certain amount of tilting of said rear elementrelative to said axis during assembly, whereby in assembling theapparatus the front end of said rear element may be readily moved pastsaid gas discharge duct and connected to the front element after saidfront element has been secured to said transmission housing and prior toinsertion of said bearing unit.
 7. Marine propulsion apparatuscomprising a front tubular element and a rear tubular element, theinterior surface of said front element being in the form of a surface ofrevolution about a central axis, the rear end of said front elementconforming in size and shape to the front end of said rear element,releasable means securing said front end of said rear element to therear end of said front element in fixed, contiguous relation, wherebysaid elements constitute a single continuous tubular casing, a bearingsupport within said rear element, said support baving an openingtherethrough co-axial with said axis, means connecting said support infixed relation to and spaced from the interior surface of said rearelement, a bearing unit disposed in said opening, said bearing unithaving an internal bearing surface coaxial with said axis and beinginsertable into and removable from said opening through the rear end ofsaid rear element, means releasably connecting said bearing unit infixed relation to said support, an outboard motor transmission housing,means securing the front end of said front element to said housing, apower-driven shaft extending rearwardly from said housing in alignmentwith said axis, the rear end of said shaft being rotatably supported insaid bearing unit, and a bladed impeller unit in said front elementmounted on said shaft for retation therewith, wherein said bearing unithas an outwardly extending forwardly facing shoulder at its rear endengageable with the rear end of said support, thereby limiting to apredetermined position the forward displacement of said unit relative tosaid support.
 8. The structure recited in claim 7 and wherein saidbearing unit is characterized by internal passageways providingcommunication between said bearing surface and the rear end of saidtubular casing, and said bearing support and bearing unit are axiallyspaced from said impeller unit to provide communication between saidbearing surface and the front end of said tubular casing, whereby alubricating flow of water through the bearing is obtained during thenormal operation of said apparatus.
 9. The structure recited in claim 8and wherein said support and sAid bearing unit in assembled conditionform a fairing element having a rearwardly tapered, streamlined outersurface.
 10. The structure recited in claim 9 and wherein said bearingsurface is made of rubber formed with longitudinally disposed grooves.11. Marine propulsion apparatus comprising a front tubular element and arear tubular element, the interior surface of said front element beingin the form of a surface of revolution about a central axis, the rearend of said front element conforming in size and shape to the front endof said rear element, releasable means securing said front end of saidrear element to the rear end of said front element in fixed, contiguousrelation, whereby said elements constitute a single continuous tubularcasing, a bearing support within said rear element, said support havingan opening therethrough co-axial with said axis, means connecting saidsupport in fixed relation to and spaced from the interior surface ofsaid rear element, a bearing unit disposed in said opening, said bearingunit having an internal bearing surface co-axial with said axis andbeing insertable into and removable from said opening through the rearend of said rear element, means releasably connecting said bearing unitin fixed relation to said support, an outboard motor transmissionhousing, means securing the front end of said front element to saidhousing, a power-driven shaft extending rearwardly from said housing inalignment with said axis, the rear end of said shaft being rotatablysupported in said bearing unit, and a bladed impeller unit in said frontelement mounted on said shaft for rotation therewith, wherein saidbearing unit is characterized by internal passageways providingcommunication between said bearing surface and the rear end of saidtubular casing, and said bearing support and bearing unit are axiallyspaced from said impeller unit to provide communication between saidbearing surface and the front end of said tubular casing, whereby alubricating flow of water through the bearing is obtained during thenormal operation of said apparatus.
 12. The structure recited in claim 1and wherein said bearing unit is characterized by internal passagewaysproviding communication between said bearing surface and the rear end ofsaid tubular casing, and said bearing support and bearing unit areaxially spaced from said impeller unit to provide communication betweensaid bearing surface and the front end of said tubular casing, whereby alubricating flow of water through the bearing is obtained during thenormal operation of said device.
 13. The structure recited in claim 1and wherein the transverse dimensions of said opening are such as topermit a certain amount of tilting of said rear element relative to saidaxis during assembly, whereby in assembling the deivce the front end ofsaid rear element may be readily moved past said gas discharge duct andconnected to the front element after said front element has been securedto said transmission housing and prior to insertion of said bearingunit.